The invention described herein applies to the devices, generally removable, that can be used to store, and therefore transport, terminal startup and configuration data. These are, in particular, storage devices that are connected to a computer and that contain all the data needed for the startup and software configuration of the computer: operating system, user programs, user data, etc.
Such a storage device is, for example, a USB (Universal Serial Bus) key that can be connected to the USB port of a personal computer. In the memory of such a key, it is possible to store a complete operating system in a format such that, when the computer is restarted, it is this operating system that will be run. Consequently, when such a device is connected to a USB port of a personal computer and a user starts up this computer, the basic input/output system (BIOS) of the terminal detects the presence of such a device on the USB port and loads the programs that are stored therein, which in particular triggers the startup of the stored operating system.
In this startup procedure, only the software stored in the memory of the removable device is invoked, not the software initially installed on the hard disk of the computer. Such a device makes it possible to use any computer without using the programs that are stored on that computer's hard disk, and without having to fear the presence of any infected or corrupted programs.
However, given the security level expected of such removable devices, it is difficult to securely upgrade the content of the terminal's device. The user is therefore not able to have the software configuration used upgraded. Furthermore, such a removable device is likely to be hacked if it is stolen by a hacker and the software that is stored therein is modifiable.
Apart from reformatting the data storage device, there is no solution that allows both the secure configuration of the terminal from a tamper-proof startup data storage device and the secure updating of this configuration or of this device. The invention proposes a solution to this problem.